用环境变量渲染template

main.go

package main

import (
	"flag"
	"fmt"
	"os"
	"strings"
	"text/template"
)

var (
	tempfile = ""
)

func init() {
	flag.StringVar(&tempfile, "t", "", "template file")
}

func main() {
	flag.Parse()
	t, err := template.ParseFiles(tempfile)
	if err != nil {
		fmt.Fprintf(os.Stderr, "parse tempfile failed, %v\n", err)
		os.Exit(1)
	}

	data := make(map[string]string)
	for _, s := range os.Environ() {
		items := strings.SplitN(s, "=", 2)
		if len(items) != 2 {
			continue
		}
		name := items[0]
		value := items[1]
		data[name] = value
	}

	err = t.Execute(os.Stdout, data)
	if err != nil {
		fmt.Fprintf(os.Stderr, "execute template %v", err)
		os.Exit(3)
	}
}